Some entities exchange documents, such as purchase orders, order confirmations, invoices, catalogs, or advanced ship notices, that are written in commerce eXtensible Markup Language (cXML). Additionally, some Internet transactions are supported by cXML, such as real-time invoice-status updates or PunchOut. A commerce hub can establish different cXML schemas, which can be provided as nonextensible Document Type Definitions (DTDs) that can provide templates for particular types of documents or transactions. As one exemplary process flow, a sender can send a cXML document to the commerce hub, which can authenticate the sender, perform format and content validation on the document, manage security, store the document, and/or route the document to an appropriate recipient. However, the nonextensible schema (e.g., DTD) established by the commerce hub may not necessarily include all of the information that an entity wishes to include in a given document or transaction, e.g., based on a recipient request for such information. Senders can include custom information as extrinsics. The sender need not necessarily update the nonextensible schema, but instead can directly make changes to the cXML document by adding their custom extrinsics. The current non-extensible schema (e.g., DTD) already supports using extrinsics. An exemplary extrinsic is a name/value pair that can be used directly in the cXML. In addition, various senders might create their own custom extrinsics which the receiver needs to understand for mapping. In addition, many senders can end up creating their own custom extrinsic for the same functional use, which can lead to redundancy. Also, the commerce hub may not necessarily understand the value/meaning of the custom field/extrinsic. In addition, it is not necessarily easily manageable/documentable.